1. Field of the Invention
The present invention relates to an electrical socket, and more particularly to a land grid array (LGA) socket having contact terminals having contact engaging portion with uniformed pitch, and tail portion with variable pitches different to the contact engaging portion.
2. Description of Related Art
Electrical sockets includes land grid array (LGA) sockets, ball grid array (BGA) sockets and pin grid array (PGA) sockets in accordance with the contacting between terminals and a central processing unit (CPU) or a printed circuit board (PCB).
A CPU socket disclosed in U.S. Pat. No. 7,074,048 issued to Cheng on Jul. 11th, 2006 includes an insulative housing having a plurality of passageways equidistantly arrayed thereon and a plurality of conductive terminals received in the passageways of the housing, respectively. Each terminal includes a base portion, an elastic arm and a solder portion extending from opposite sides of the base portion, and a contacting portion located at a free end of the elastic arm. The solder portion has a solder ball attached thereon. The pitch of the contacting portions is equal to the pitch of the solder portions after the terminals are assembled in the housing. The socket achieves the electrical connecting between the CPU and the PCB by soldering the solder portions of the terminals to pads of the PCB and the contacting between the contacting portions and pads of the CPU.
With the trend toward miniaturization in computer technology, the LGA socket becomes more smaller while more and more contact terminals are arranged within a single socket. Due to the difference between the CPU technology and the PCB technology, new processes can obtain small pitches of the pads on the CPU. However, manufacturing the PCB having the same pad pitches with the CPU needs higher costs, and the yield of the finished products is low. The LGA socket which can only electrically connect the CPU and the PCB with the same pitches limits the development of the CPU having fine pitch pads. Additionally, using solder balls to electrically connecting with the PCB also increases the height of the CPU socket.
In view of the above, an improved CPU socket for electrically connecting the CPU with the PCB with different pitches is needed.